Techniques for using a touch screen to perform ear detection using emulated self capacitance sensing

ABSTRACT

A touch-screen-controller (TSC) performs mutual sensing to acquire touch strength values from a touch matrix formed by capacitively intersecting conductive lines. For each line, the TSC generates an emulated self capacitance value from an associated touch strength value based upon a position of that line compared to a location on the touch matrix adjacent to which a first touch type is expected to occur, and determines presence of the first touch type adjacent to the touch matrix based upon the emulated values. The emulated values for each conductive line may be weighted based upon its closeness to the location where the first touch type is expected to occur. The weighting may be zero if its associated conductive line is outside of the location where the first touch type is expected to occur, and may be one if inside of the location where the first touch type is expected to occur.

RELATED APPLICATION

This application is a continuation of U.S. application for patent Ser.No. 16/893,672, filed Jun. 5, 2020, the contents of which areincorporated by reference to the maximum extent allowable under the law.

TECHNICAL FIELD

This disclosure is related to the field of capacitive touch sensing and,in particular, to the emulation of self capacitance sensing, using touchdata collected with mutual capacitance sensing, to perform accurate eardetection.

BACKGROUND

Touch screens are prevalent in today's computing environment. Portablecomputers, desktop computers, tablets, smart phones, and smartwatchestypically employ a touch screen to gain user input for navigation andcontrol of these devices. Thus, discerning the intent of the user viatouch inputs is an important feature of a touch screen device.

Touch screens typically operate based on capacitive touch sensing, andinclude a patterned array of conductive features. For instance, thepatterned array of conductive features may include sets of lines,conductive pads, overlapping structures, interleaved structures, diamondstructures, lattice structures, and the like. By evaluating changes incapacitance at different lines or sets of lines, a user touch or hover,such as by a finger or stylus, can be detected.

Two common capacitive touch sensing modes that may be performed on touchscreens are mutual capacitance sensing and self capacitance sensing. Ina mutual self capacitance sensing mode, a drive signal is applied to asubset of the lines referred to as drive lines, and capacitance valuesare measured at a subset of the lines referred to as sense lines, withit being understood that the sense lines cross the drive lines in aspaced apart fashion therefrom. Each crossing of a drive line and asense line forms a capacitive node. Since bringing a finger orconductive stylus near the surface of the touch screen changes the localelectric field, this causes a reduction in the capacitance between thedrive lines and the sense lines (the “mutual” capacitance), and thecapacitance change at every individual capacitive node can be measuredand processed to accurately determine the touch location. Therefore, theoutput of mutual capacitance sensing is a two-dimensional matrix ofvalues, with one value for each capacitive node (crossing between adrive line and a sense line). Thus, it can be appreciated that mutualcapacitance sensing allows multi-touch operation where multiple fingers,palms or styli can be accurately tracked at the same time.

In a self capacitance sensing mode, the drive signal is applied to everyline, regardless of orientation. Bringing a finger or conductive stylusnear the surface of the sensor changes the local electric field,increasing the capacitance between the drive line or sense line ofinterest and ground (the “self capacitance”) in this instance. However,since all lines are driven, the capacitance change can only be measuredon each line. Therefore, the output of self capacitance sensing is twoone dimensional arrays of values, with one value for each line.

There is an increasing demand for smartphones having a touch screen thatspans across the full front side of the smartphone, without largecutouts or large bezels permitting the presence of numerous sensors onthe front side of the smartphone. In particular, it is desired to removeproximity sensors from the front side of smartphones, and to insteadutilize the touch screen itself to perform the function of a proximitysensor (which is used by the smartphone to determine when the user isholding the smartphone next to their ear to make a voice call).

While conventional touch screens may be capable of performing thefunction of a proximity sensor when operating using self capacitancesensing, issues arise when it is desired to make a particularly thintouch screen perform the function of a proximity sensor. For example, inthin touch screen technology, the touch sensors themselves become moreinfluenced by and exposed to display noise, resulting in signal to noiseratio too poor to utilize self capacitance sensing in performing thefunction of a proximity sensor. As such, further development is needed.

SUMMARY

Disclosed herein is a touch screen controller including processingcircuitry. The processing circuitry is configured to perform mutualcapacitance sensing to acquire touch strength values from a capacitivetouch matrix formed by capacitively intersecting drive lines and senselines, and for each sense line, sum the touch strength values associatedwith that sense line to thereby form an emulated self capacitance sensevalue for that sense line, and apply a weighting to that emulated selfcapacitance sense value, the weighting being based upon a position ofthat sense line compared to a location on the capacitive touch matrixadjacent which a user's ear is expected to be placed. For each driveline, the processing circuitry is further configured to sum the touchstrength values associated with that drive line to thereby form anemulated self capacitance drive value for that drive line, and apply aweighting to that emulated self capacitance drive value, the weightingbeing based upon a position of that drive line compared to the locationon the capacitive touch matrix adjacent which the user's ear is expectedto be placed. The processing circuitry is also configured to determinepresence of the user's ear adjacent to the capacitive touch matrix basedupon the emulated self capacitance sense values and the emulated selfcapacitance drive values.

The weighting of each emulated self capacitance sense value may begreater the closer its associated sense line is to the location on thecapacitive touch matrix adjacent which the user's ear is expected to beplaced and lesser the farther its associated sense line is from thelocation on the capacitive touch matrix adjacent which the user's ear isexpected to be placed. The weighting of each emulated self capacitancedrive value may be greater the closer its associated drive line is tothe location on the capacitive touch matrix adjacent which the user'sear is expected to be placed and lesser the farther its associated driveline is from the location on the capacitive touch matrix adjacent whichthe user's ear is expected to be placed.

The weighting of each emulated self capacitance sense value may be aweighting of zero if its associated sense line is outside of thelocation on the capacitive touch matrix adjacent which the user's ear isexpected to be placed, and a weighting of one if its associated senseline is inside of the location on the capacitive touch matrix adjacentwhich the user's ear is expected to be placed. The weighting of eachemulated self capacitance drive value may be a weighting of zero if itsassociated drive line is outside of the location on the capacitive touchmatrix adjacent which the user's ear is expected to be placed, and aweighting of one if its associated drive line is inside of the locationon the capacitive touch matrix adjacent which the user's ear is expectedto be placed.

The weighting of each emulated self capacitance sense value may be aweighting of zero if its associated sense line is inside of a locationon the capacitive touch matrix adjacent which the user's hand isexpected to be placed. The weighting of each emulated self capacitancedrive value may be a weighting of zero if its associated sense line isinside of a location on the capacitive touch matrix adjacent which theuser's hand is expected to be placed.

Also disclosed herein is a smartphone including a portable housing, anda touch screen carried by the portable housing on a front face thereof,with the touch screen including a capacitive touch matrix formed bycapacitively intersecting drive lines and sense lines. A speaker iscarried by the portable housing at a top of the front face. A touchscreen controller within the portable housing includes drive circuitryconfigured to apply a drive signal to the drive lines, sense circuitryconfigured to sense mutual capacitances between the capacitiveintersections of the drive lines and the sense lines, and processingcircuitry. The processing circuitry is configured to acquire touchstrength values from the sense lines while the drive signal is appliedto the drive lines, and for each sense line, sum the touch strengthvalues associated with that sense line to thereby form an emulated selfcapacitance sense value for that sense line, and apply a weighting tothat emulated self capacitance sense value, the weighting being basedupon a position of that sense line on the front face of the portablehousing compared to the position of the speaker on the front face of theportable housing. The processing circuitry is also configured to, foreach drive line, sum the touch strength values associated with thatdrive line to thereby form an emulated self capacitance drive value forthat drive line, and apply a weighting to that emulated self capacitancedrive value, the weighting being based upon a position of that driveline on the front face of the portable housing compared to the positionof the speaker on the front face of the portable housing. The processingcircuitry also determines presence of the user's ear adjacent to thecapacitive touch matrix based upon the emulated self capacitance sensevalues and the emulated self capacitance drive values.

The weighting of each emulated self capacitance sense value may begreater the closer its associated sense line is to the position of thatsense line on the front face of the portable housing and lesser thefarther its associated sense line is from the position of the speaker onthe front face of the portable housing. The weighting of each emulatedself capacitance drive value may be greater the closer its associateddrive line is to the location on the capacitive touch matrix adjacentwhich the user's ear is expected to be placed and lesser the farther itsassociated drive line is from the position of the speaker on the frontface of the portable housing.

The weighting of each emulated self capacitance sense value may be aweighting of zero if its associated sense line is outside of a zonedefined around the speaker, and a weighting of one if its associatedsense line is inside of the zone defined around the speaker.

The weighting of each emulated self capacitance sense value may be aweighting of zero if its associated sense line is inside of a locationon the capacitive touch matrix adjacent which the user's hand isexpected to be placed. The weighting of each emulated self capacitancedrive value may be a weighting of zero if its associated sense line isinside of a location on the capacitive touch matrix adjacent which theuser's hand is expected to be placed.

Also disclosed herein is a method including acquiring touch strengthvalues from a capacitive touch matrix formed by capacitivelyintersecting drive lines and sense lines, using mutual capacitancesensing, and for each sense line, summing the touch strength valuesassociated with that sense line to thereby form an emulated selfcapacitance sense value for that sense line, and apply a weighting tothat emulated self capacitance sense value, the weighting being basedupon the position of that sense line compared to a location on thecapacitive touch matrix adjacent which a user's ear is expected to beplaced. The method also includes for each drive line, summing the touchstrength values associated with that drive line to thereby form anemulated self capacitance drive value for that drive line, and apply aweighting to that emulated self capacitance drive value, the weightingbeing based upon the position of that drive line compared to thelocation on the capacitive touch matrix adjacent which the user's ear isexpected to be placed. The method further includes determining presenceof the user's ear adjacent to the capacitive touch matrix based upon theemulated self capacitance sense values and the emulated self capacitancedrive values.

The weighting of each emulated self capacitance sense value may begreater the closer its associated sense line is to the location on thecapacitive touch matrix adjacent which the user's ear is expected to beplaced and lesser the farther its associated sense line is from thelocation on the capacitive touch matrix adjacent which the user's ear isexpected to be placed. The weighting of each emulated self capacitancedrive value may be greater the closer its associated drive line is tothe location on the capacitive touch matrix adjacent which the user'sear is expected to be placed and lesser the farther its associated driveline is from the location on the capacitive touch matrix adjacent whichthe user's ear is expected to be placed.

The weighting of each emulated self capacitance sense value may be aweighting of zero if its associated sense line is outside of thelocation on the capacitive touch matrix adjacent which the user's ear isexpected to be placed, and a weighting of one if its associated senseline is inside of the location on the capacitive touch matrix adjacentwhich the user's ear is expected to be placed. The weighting of eachemulated self capacitance drive value may be a weighting of zero if itsassociated drive line is outside of the location on the capacitive touchmatrix adjacent which the user's ear is expected to be placed, and aweighting of one if its associated drive line is inside of the locationon the capacitive touch matrix adjacent which the user's ear is expectedto be placed.

The weighting of each emulated self capacitance sense value may be aweighting of zero if its associated sense line is inside of a locationon the capacitive touch matrix adjacent which the user's hand isexpected to be placed. The weighting of each emulated self capacitancedrive value may be a weighting of zero if its associated sense line isinside of a location on the capacitive touch matrix adjacent which theuser's hand is expected to be placed.

Also disclosed herein is a touch screen controller, including processingcircuitry configured to perform mutual capacitance sensing to acquiretouch strength values from a capacitive touch matrix formed bycapacitively intersecting conductive lines, for each conductive line,generate an emulated self capacitance value from an associated touchstrength value based upon a position of that conductive line compared toa location on the capacitive touch matrix adjacent to which a firsttouch type is expected to occur, and determine presence of the firsttouch type adjacent to the capacitive touch matrix based upon theemulated self capacitance values.

The processing circuitry may be configured to generate the emulated selfcapacitance values for each conductive line by weighting the acquiredtouch strength values based upon its closeness to the location on thecapacitive touch matrix adjacent to which the first touch type isexpected to occur.

The weighting applied to each acquired touch strength value may be aweighting of zero if its associated conductive line is outside of thelocation on the capacitive touch matrix adjacent which the first touchtype is expected to occur, and a weighting of one if its associatedconductive line is inside of the location on the capacitive touch matrixadjacent which the first touch type is expected to occur.

The weighting applied to each acquired touch strength value may be aweighting of one if its associated conductive line is outside of thelocation on the capacitive touch matrix adjacent which a second touchtype is expected to occur, and a weighting of zero if its associatedconductive line is inside of the location on the capacitive touch matrixadjacent which the first touch type is expected to occur, wherein thesecond touch type is different than the first touch type.

The first touch type may be a touch by a portion of a user's head, andthe second touch type may be a touch by a portion of a user's hand.

The conductive lines may include capacitively intersecting drive linesand sense lines. The processing circuitry may be configured to generatethe emulated self capacitance value for each conductive line by for eachsense line, generating an emulated self capacitance sense value basedupon a position of that sense line compared to a location on thecapacitive touch matrix adjacent to which the first touch type isexpected to occur, and for each drive line, generate an emulated selfcapacitance drive value based upon a position of that drive linecompared to the location on the capacitive touch matrix adjacent towhich the first touch type is expected to occur. The processingcircuitry may be configured to determine the presence of the first touchtype adjacent to the capacitive touch matrix based upon the emulatedself capacitance sense values and emulated self capacitance drivevalues.

The processing circuitry may be configured to generate the emulated selfcapacitance sense values by acquiring touch strength values for thesense lines and weighting those touch strength values based on theircloseness to the location on the capacitive touch matrix adjacent towhich the first touch type is expected to occur. The processingcircuitry may be configured to generate the emulated self capacitancedrive values by acquiring touch strength values for the drive lines andweighting those touch strength values based on their closeness to thelocation on the capacitive touch matrix adjacent to which the firsttouch type is expected to occur.

The weighting applied to each touch strength value for the sense linesmay be a weighting of zero if its associated sense line is outside ofthe location on the capacitive touch matrix adjacent which the firsttouch type is expected to occur, and a weighting of one if itsassociated sense line is inside of the location on the capacitive touchmatrix adjacent which the first touch type is expected to occur.

The weighting applied to each touch strength value for the drive linesmay be a weighting of zero if its associated drive line is outside ofthe location on the capacitive touch matrix adjacent which the firsttouch type is expected to occur, and a weighting of one if itsassociated drive line is inside of the location on the capacitive touchmatrix adjacent which the first touch type is expected to occur.

The weighting applied to each touch strength value for the sense linesmay be a weighting of one if its associated sense line is outside of thelocation on the capacitive touch matrix adjacent which a second touchtype is expected to occur, and a weighting of zero if its associatedsense line is inside of the location on the capacitive touch matrixadjacent which the second touch type is expected to occur.

The weighting applied to each touch strength value for the drive linesmay be a weighting of one if its associated drive line is outside of thelocation on the capacitive touch matrix adjacent which a second touchtype is expected to occur, and a weighting of zero if its associateddrive line is inside of the location on the capacitive touch matrixadjacent which the second touch type is expected to occur.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a touch screen device such as may be usedfor performing the functions described herein.

FIG. 2 is a block diagram of the touch screen of the touch screen deviceof FIG. 1.

FIG. 3 is the capacitive touch matrix of the touch screen of FIGS. 1-2represented generally.

FIG. 4 is a flowchart showing operation of the touch screen device ofFIG. 1 when performing the functions described herein.

FIG. 5 is a chart showing touch strength values collected using mutualcapacitance sensing as summed and used to emulate touch strength valuescollected using self capacitance sensing, so as to permit ear detection.

FIG. 6 is a chart showing touch strength values collected using mutualcapacitance sensing as summed and weighted to be used to emulate touchstrength values collected using self capacitance sensing, so as topermit ear detection.

DETAILED DESCRIPTION

The following disclosure enables a person skilled in the art to make anduse the subject matter disclosed herein. The general principlesdescribed herein may be applied to embodiments and applications otherthan those detailed above without departing from the spirit and scope ofthis disclosure. This disclosure is not intended to be limited to theembodiments shown, but is to be accorded the widest scope consistentwith the principles and features disclosed or suggested herein.

FIG. 1 is a functional block diagram of a touch screen device 100according to an embodiment as disclosed herein. The touch screen device100 may be a smartphone, tablet, portable computer, smartwatch,wearable, or other device. The touch screen device 100 includes atactile input surface, such as a touch screen display 110, coupled to atouch screen controller 120. The touch screen display 110 is designed toreceive touch inputs from a user through a user's fingers or a stylus.

The touch screen display 110 includes a display layer 113 and a touchsensing layer 111 (shown in FIG. 2). The touch sensing layer 111 iscomprised of touch screen sensors 115 that are configured to detecttouches (or other input actions such as hover or gesture motions) to thetouch screen display 110. As a touch is sensed, the touch screencontroller 120 may receive touch signals from the sensors 115 via sensecircuitry 122 and analyze the touch signal(s) using processing circuitry124. This analysis produces coordinates of the received touch. Thesecoordinates may then be used by a system on a chip (SOC) 130 tomanipulate operations with respect to applications and programsexecuting on the touch screen device 100.

It is noted that the same sensors 115 are capable of being used for bothself-capacitance sensing and mutual capacitance sensing, and thattherefore both the sense circuitry 122 and the processing circuitry 124are likewise capable of operating in both self-capacitance sensing andmutual sensing modes.

As shown in FIG. 3, patterned lines, namely conductive rows (sense linesS1-S4) and columns (drive lines D1-D4), are formed in the touch sensinglayer 111. The intersections of the columns and rows form the individualcapacitive touch sensors 115 during mutual capacitance touch sensing,and the processing circuitry 124 scans these touch sensors and processesthe generated signals to identify the location and type of a touch pointor points. Thus, the touch screen display 110 may be considered asproducing a touch map having XY coordinates wherein several touchregions (as defined by a set of XY coordinates) of possible touchinformation may be generated based on one or more touches to the touchscreen display 110. The coordinates generated above are XY coordinatesidentifying the location of the touch on the touch screen display 110.

Note that although the sense lines S1-S4 and drive lines D1-D4 aredepicted in FIG. 4 as being straight conductive lines orthogonal to oneanother, in actuality they may take any shape.

In the mutual capacitance sensing mode, a drive signal is applied to thedrive lines D1-D4 by drive circuitry 121, and capacitance values aremeasured at the sense lines S1-S4 by the sense circuitry 122. Sincebringing a finger or conductive stylus near the surface of the sensorchanges the local electric field, this causes a reduction in the mutualcapacitance between the drive lines and the sense lines, and thecapacitance change at every individual point on the grid can be measuredto accurately determine the touch location. Therefore, the output ofmutual capacitance sensing is a two-dimensional matrix of values, withone value for each intersection between conductive lines. Thus, it canbe appreciated that mutual capacitance sensing allows multi-touchoperation where multiple fingers, palms or styli can be accuratelytracked at the same time.

Operation of the touch screen display 110 and touch screen controller120 when performing touch sensing, including ear detection, is nowdescribed with additional reference to FIG. 4. The touch screencontroller 120 switches between performing normal touch detection usingmutual and/or self capacitance sensing (Block 201), and operating solelyin mutual capacitance sensing mode with an increased gain so as toperform ear detection (Block 203).

When performing normal touch detection using mutual and/or selfcapacitance sensing (Block 201), the touch screen controller 120processes the collected touch strength values to determine thecoordinates of the touch, and then reports the touch coordinates to theSOC 130.

When performing ear detection (Block 203), the touch screen controller120 acquires touch strength values from the touch screen display 110solely using mutual capacitance sensing, and then generates sense lineand drive line strength values (Block 204), referred to a emulated selfcapacitance values, that emulate what those values would be if they hadinstead been acquired using self capacitance sensing. Note that theemulated self capacitance values (referred to below as emulated sensevalues and emulated drive values) are not acquired or obtained usingself capacitance sensing, and are not determined from any touch strengthvalues acquired using self capacitance sensing. Instead, the emulatedself capacitance values are calculated (not acquired), and thiscalculation is performed solely and exclusively using touch strengthvalues acquired using mutual capacitance sensing.

This is now described in greater detail with reference to FIGS. 5-6,which shows a sample set of touch strength values acquired using mutualcapacitance sensing. To produce the emulated sense line and drive linestrength values, the touch screen controller 120 sums each column oftouch strength values that were acquired using mutual capacitancesensing to produce a single and exclusive emulated self capacitancetouch strength value for that column, and sums each row of touchstrength values that were acquired using mutual capacitance sensing toproduce a single and exclusive emulated self capacitance touch strengthvalue for that row. In the illustrated example of the touch sensinglayer 111 shown in FIG. 3, note that the rows are driven while thecolumns are sensed during mutual capacitance sensing, so the singleemulated self capacitance touch strength value for each column can, asshorthand, be referred to as an emulated “sense” value, while the singleemulated self capacitance touch strength value for each row can, asshorthand, be referred to as an emulated “drive” value.

When a user uses a smartphone to place a voice call, the user typicallyplaces his ear near to the speaker, which is typically located towardthe “top” of the front side of the smartphone. For this reason, priorart smartphones that use proximity sensors to detect a user's ear placethose proximity sensors near the top of the front side of thesmartphone, and then turn off the touch screen while the user's ear isin proximity. Due to the use of a proximity sensor to perform thisproximity sensing, such prior art smartphones may completely turn offtouch sensing when the user's ear is detected.

To address the above, when the touch screen controller 120 operates toperform ear detection, the emulated sense values are weighted, withhigher weights being applied to the emulated sense values correspondingto sense lines near the top of the front side of the smart phone, andlesser weights being applied to the emulated sense values correspondingto sense lines farther from the top of the front side of the smartphone. In some cases, the emulated drive values are also weighted, withhigher weights being applied to the emulated drive values correspondingto drive lines farther from the edges of the touch screen display 110,and lesser weights being applied to the emulated drive valuescorresponding to drive lines closer to the edges of the touch screendisplay 110. This weighting may be performed to remove the effects ofthe user's hand (holding the smartphone) on touch sensing. Weighting mayalso be applied to emphasize the touch strength values in region on thetouch screen display 110 adjacent to which the user is expected to placetheir ear, thereby effectively increasing the gain of those touchstrength values.

An example of this weighting can be seen in FIG. 6, where the bottomleftmost touch strength value can be referred to as having thecoordinates (0,0), and where the top rightmost touch strength value canbe referred to as having the coordinates (X,Y). Therefore, note thatfrom left to right, the columns (sense lines) are numbered from 0 to X,and that from bottom to top, the rows (drive lines) are numbered from 0to Y.

For simplicity of explanation here, instead of progressive weighting,weights of either 0 or 1 are applied to the various emulated drive andsense values. In particular, a weight of 0 is applied to emulated drivevalues in rows 0 and Y to cancel out the effects of the user's hand onthe touch screen 110, and a weight of 0 is applied to emulated sensevalues in columns 0 to 12 to emphasize the touch strength values in theregion on the touch screen display 110 adjacent to which the user isexpected to place their ear. A weight of 1 is applied to the otheremulated drive values and emulated sense values. Therefore, reviewingthe area of the chart of FIG. 5 labeled as “Ear close to this region”,it can be seen that in the chart of FIG. 6, the corresponding sense anddrive lines have had the weight of 1 applied thereto, while the othersense and drive lines have had the weight of 0 applied thereto.

It should be appreciated that there may be multiple levels and types ofweighting applies. For example, a first weighting scheme may be appliedto emulated sense values and emulated drive values associated with areasof the touch screen 110 where the user is expected to place their hand(grasp the smartphone) while performing a voice call, such as byapplying a weight of 0 to those emulated sense values and emulated drivevalues, and a second weighting scheme (such as a progressive weighting)may be applied to emulated sense values and emulated drive valuesassociated with an area of the touch screen 110 where the user isexpected to place their ear while performing a voice call.

Therefore, understand that overall, the goal of the weighting is toemphasize the emulated sense values and emulated drive values associatedwith the area of the touch screen 110 where the user is expected toplace their ear while performing a voice call, while removing ordeemphasizing emulated sense values and emulated drive values outside ofthis area.

Mathematically, the calculation of the emulated sense values from thetouch strength values obtained using mutual capacitance sensing can becalculated as:

eS(x)=w(x)*Σ_(x=X,y=o) ^(x=X,y=Max(y)) m(x,y)

where w(x) is the weight to be applied to that emulated sense value(which, as explained, is based upon which sense line that emulated sensevalue represents), and where m(x,y) represents the touch strength valuesobtained using mutual capacitance sensing.

Similarly, mathematically, the calculation of the emulated drive valuesfrom the touch strength values obtained using mutual capacitance sensingcan be calculated as:

eF(yx)=w(y)Σ_(x=0,y=Y) ^(x=Max(x),y=Y) m(x,y)

where w(x,y) is the weight to be applied to that emulated drive value(which, as explained, is based upon which drive line that emulated drivevalue represents), and where m(x,y) represents the touch strength valuesobtained using mutual capacitance sensing.

Once each emulated sense value (one per sense line) and once eachemulated drive value (one per drive line) has been calculated by thetouch screen controller 120, then (referring back to FIG. 4), the touchscreen controller 120 passes the emulated sense and drive values to anapplication executed either via the processing circuitry 124 or the SOC130 that performs the actual ear detection on the emulated sense andemulated drive values (Block 205). Based on detection of the user's ear,the SOC 103 can, for example, turn off the touch screen so that theuser's ear does not cause inadvertent user input while the user isconducting a voice call.

The techniques described above for calculating the emulated sense valuesand emulated drive values are advantageous because the emulated valueshave similar characteristics as touch strength values acquired usingself capacitance sensing, but are calculated using touch strength valuesacquired using mutual capacitance sensing, which has a greater signal tonoise ratio than touch strength values acquired using self capacitancesensing in a thin touch screen display 110, such as a Youm On-Cell TouchAMOLED display (Y-OCTA).

Those of skill in the art will appreciate that, despite the techniquesabove being described with respect to performing ear detection, theemulated sense values and emulated drive values can be used forperforming any sort of proximity detection (for example, for performinghover detection).

While the disclosure has been described with respect to a limited numberof embodiments, those skilled in the art, having benefit of thisdisclosure, will appreciate that other embodiments can be envisionedthat do not depart from the scope of the disclosure as disclosed herein.Accordingly, the scope of the disclosure shall be limited only by theattached claims.

1. A touch screen controller, comprising: processing circuitryconfigured to: perform mutual capacitance sensing to acquire touchstrength values from a capacitive touch matrix formed by capacitivelyintersecting conductive lines; for each conductive line, generate anemulated self capacitance value from an associated touch strength valuebased upon a position of that conductive line compared to a location onthe capacitive touch matrix adjacent to which a first touch type isexpected to occur; and determine presence of the first touch typeadjacent to the capacitive touch matrix based upon the emulated selfcapacitance values.
 2. The touch screen controller of claim 1, whereinthe processing circuitry is configured to generate the emulated selfcapacitance values for each conductive line by weighting the acquiredtouch strength values based upon its closeness to the location on thecapacitive touch matrix adjacent to which the first touch type isexpected to occur.
 3. The touch screen controller of claim 2, whereinthe weighting applied to each acquired touch strength value is aweighting of zero if its associated conductive line is outside of thelocation on the capacitive touch matrix adjacent which the first touchtype is expected to occur, and a weighting of one if its associatedconductive line is inside of the location on the capacitive touch matrixadjacent which the first touch type is expected to occur.
 4. The touchscreen controller of claim 2, wherein the weighting applied to eachacquired touch strength value is a weighting of one if its associatedconductive line is outside of the location on the capacitive touchmatrix adjacent which a second touch type is expected to occur, and aweighting of zero if its associated conductive line is inside of thelocation on the capacitive touch matrix adjacent which the first touchtype is expected to occur, wherein the second touch type is differentthan the first touch type.
 5. The touch screen controller of claim 4,wherein the first touch type is a touch by a portion of a user's head;and wherein the second touch type is a touch by a portion of a user'shand.
 6. The touch screen controller of claim 1, wherein the conductivelines comprise capacitively intersecting drive lines and sense lines;wherein the processing circuitry is configured to generate the emulatedself capacitance value for each conductive line by: for each sense line,generating an emulated self capacitance sense value based upon aposition of that sense line compared to a location on the capacitivetouch matrix adjacent to which the first touch type is expected tooccur; and for each drive line, generate an emulated self capacitancedrive value based upon a position of that drive line compared to thelocation on the capacitive touch matrix adjacent to which the firsttouch type is expected to occur; and wherein the processing circuitry isconfigured to determine the presence of the first touch type adjacent tothe capacitive touch matrix based upon the emulated self capacitancesense values and emulated self capacitance drive values.
 7. The touchscreen controller of claim 6, wherein the processing circuitry isconfigured to generate the emulated self capacitance sense values byacquiring touch strength values for the sense lines and weighting thosetouch strength values based on their closeness to the location on thecapacitive touch matrix adjacent to which the first touch type isexpected to occur; and wherein the processing circuitry is configured togenerate the emulated self capacitance drive values by acquiring touchstrength values for the drive lines and weighting those touch strengthvalues based on their closeness to the location on the capacitive touchmatrix adjacent to which the first touch type is expected to occur. 8.The touch screen controller of claim 7, wherein the weighting applied toeach touch strength value for the sense lines is a weighting of zero ifits associated sense line is outside of the location on the capacitivetouch matrix adjacent which the first touch type is expected to occur,and a weighting of one if its associated sense line is inside of thelocation on the capacitive touch matrix adjacent which the first touchtype is expected to occur.
 9. The touch screen controller of claim 7,wherein the weighting applied to each touch strength value for the drivelines is a weighting of zero if its associated drive line is outside ofthe location on the capacitive touch matrix adjacent which the firsttouch type is expected to occur, and a weighting of one if itsassociated drive line is inside of the location on the capacitive touchmatrix adjacent which the first touch type is expected to occur.
 10. Thetouch screen controller of claim 7, wherein the weighting applied toeach touch strength value for the sense lines is a weighting of one ifits associated sense line is outside of the location on the capacitivetouch matrix adjacent which a second touch type is expected to occur,and a weighting of zero if its associated sense line is inside of thelocation on the capacitive touch matrix adjacent which the second touchtype is expected to occur.
 11. The touch screen controller of claim 7,wherein the weighting applied to each touch strength value for the drivelines is a weighting of one if its associated drive line is outside ofthe location on the capacitive touch matrix adjacent which a secondtouch type is expected to occur, and a weighting of zero if itsassociated drive line is inside of the location on the capacitive touchmatrix adjacent which the second touch type is expected to occur.
 12. Amethod, comprising: acquiring touch strength values from a capacitivetouch matrix formed by capacitively intersecting conductive lines, usingmutual capacitance sensing; for each conductive line, generating anemulated self capacitance value from an associated touch strength valuebased upon a position of that conductive line compared to a location onthe capacitive touch matrix adjacent to which a first touch type isexpected to occur; and determining presence of the touch adjacent to thecapacitive touch matrix based upon the emulated self capacitance values.13. The method of claim 12, wherein the emulated self capacitance valuesare generated for each conductive line by weighting the associated touchstrength value based upon its closeness to the location on thecapacitive touch matrix adjacent to which the first touch type isexpected to occur.
 14. The method of claim 13, wherein the weightingapplied to each touch strength value is a weighting of zero if itsassociated conductive line is outside of the location on the capacitivetouch matrix adjacent which the first touch type is expected to occur,and a weighting of one if its associated conductive line is inside ofthe location on the capacitive touch matrix adjacent which the firsttouch type is expected to occur.
 15. The method of claim 13, wherein theweighting applied to each touch strength value is a weighting of one ifits associated conductive line is outside of the location on thecapacitive touch matrix adjacent which a second touch type is expectedto occur, and a weighting of zero if its associated conductive line isinside of the location on the capacitive touch matrix adjacent which thefirst touch type is expected to occur, wherein the second touch type isdifferent than the first touch type.
 16. A method, comprising: acquiringtouch strength values from a capacitive touch matrix formed bycapacitive intersecting drive lines and sense lines; for each senseline, generating an emulated self capacitance sense value from anassociated touch strength value based upon a position of that sense linecompared to a location on the capacitive touch matrix adjacent to whicha first touch type is expected to occur; for each drive line, generatean emulated self capacitance drive value from an associated touchstrength value based upon a position of that drive line compared to thelocation on the capacitive touch matrix adjacent to which the firsttouch type is expected to occur; and determining presence of the firsttouch type adjacent to the capacitive touch matrix based upon theemulated self capacitance sense values and emulated self capacitancedrive values.
 17. The method of claim 16, wherein the emulated selfcapacitance sense values are generated by weighting the associated touchstrength values based on their closeness to the location on thecapacitive touch matrix adjacent to which the first touch type isexpected to occur; and wherein the emulated self capacitance drivevalues are generated by weighting the associated touch strength valuesbased on their closeness to the location on the capacitive touch matrixadjacent to which the first touch type is expected to occur.
 18. Themethod of claim 17, wherein the weighting applied to a given touchstrength value is a weighting of zero if its associated sense line isoutside of the location on the capacitive touch matrix adjacent whichthe first touch type is expected to occur, and a weighting of one if itsassociated sense line is inside of the location on the capacitive touchmatrix adjacent which the first touch type is expected to occur.
 19. Themethod of claim 17, wherein the weighting applied to a given touchstrength value is a weighting of zero if its associated drive line isoutside of the location on the capacitive touch matrix adjacent whichthe first touch type is expected to occur, and a weighting of one if itsassociated drive line is inside of the location on the capacitive touchmatrix adjacent which the first touch type is expected to occur.
 20. Themethod of claim 17, wherein the weighting applied to a given touchstrength value is a weighting of one if its associated sense line isoutside of the location on the capacitive touch matrix adjacent which asecond touch type is expected to occur, and a weighting of zero if itsassociated sense line is inside of the location on the capacitive touchmatrix adjacent which the second touch type is expected to occur. 21.The method of claim 17, wherein the weighting applied to a given touchstrength value is a weighting of one if its associated drive line isoutside of the location on the capacitive touch matrix adjacent which asecond touch type is expected to occur, and a weighting of zero if itsassociated drive line is inside of the location on the capacitive touchmatrix adjacent which the second touch type is expected to occur.